Rotary jig and methods for treating iron ore



A. A. HOOD 2,925,179

ROTARY JIG AND METHODS FOR TREATING IRON ORE Feb. 16, 1960 Filed May 27, 1955 VEN TOR.

ATTpRNE Y5 United States Patent ROTARY JIG AND METHODS FOR TREATING IRON ORE Alva A. Bond, Idaho Springs, Colo. Application May 27, 1955, Serial No. 511,500 14 Claims. (Cl. 209-455) This invention relates to methods of treating solids in liquids and to apparatus for concentrating, desliming and classifying solids in liquids.

The present invention is particularly adapted for, but not limited to, a treatment of materials in finely divided condition, particularly products screened to a 10 mesh size range. As an example, the invention may be utilized in treating the tailings of taconite ore processing plants in which the ore contains such a small amount of magnetic material that it is not feasible to attempt its recovery with magnetic separators. Usually the tonnage capacity of such plants is so large that a considerable quantity of valuable product iswasted during a seasonal operation.

j The apparatus of the present invention may be classed as a rotary jig but differs from the usual jigging operation in that the heavier constituent is not discharged to the atmosphere or into a static body of liquid. In the practice of the present invention, a settled product is removed in an induced flow, preferably at an elevated point of discharge, by the action of a diaphragm pump. A hydraulic pulsation is utilized to provide the jigging action or teeter effect and the pulsations are directed or restricted at the lower end of the settling zone to produce an intermittent upcast flow which is finally dissipated in a body of material moving under centrifugal influence and maintained in a relatively high density condition.

As a consequence of these variations from the usual procedures, it is possible to treat an ore pulp or the like having constituents of substantially different specific gravity or in a substantial size range to obtain a clean concentrate or a closely sized end product. The practice of the invention will be best understood by reference to the accompanying drawings.

.. In the drawings:

Fig. 1 is a vertical central section through a treatment tank embodying features of this invention with associated parts shown in elevation;

Fig. 2 is an enlarged fragmentary section of the teeter bed shown in Fig. 1.

As shown in Fig. 1, the apparatus comprises a cylindrical tank 3 having a circumferential overflow 4 atits top and a conical bottom portion 5 terminating at its lower end in a tubular extension portion 6 constituting the vertical treatment zone which will be described more fully hereinafter. Feed issupplied to the top of tank 3 through a central inlet member 7 and the contents of the tank are maintained in centrifugal movement. by the rotation of an impeller 8 driven by a motor and speed reducer unit 9. N

In preferred practice, the tubular extension 6 is formed by a series of interconnected flanged members with the final discharge moving through an upstanding conduit 12 connected with a diaphragm ard type. Examples of such scribed in Taggart edition,

pumps are shown and de- Handbook of Mineral Dressing, 1947 pump unit 13 of any stand- Section 18-89. -A reservoir 14 supplies water through a bypass line 15 into the lower end of line 12,- and a valve 16 is provided to control the volume of water so delivered. Water is delivered continuously into reser-- voir 14 from a suitable source (not shown) and such water is removed through an outlet 20 and may be recirculated where water conservation is required. The head of water above out-let 20 may be selectively varied by changing the overflow level of a tube 21 in telescop ing arrangement with outlet member 20.

The main flow of water from reservoir 14 passes through a line 22 preferably containing a check valve 23 and fills a displacement unit 24 of a pulsator mechanism 25 from which it passes through a line 26 into a section of the vertical extension constituting the back Wash inlet 27 of the unit. An interchangeable bushing member 28 is located in the extension portion above the inlet 27 and, through selective variation of the bore of the bushing, it is possible to regulate the velocity of the' pulsating flow.

For most treatments, I prefer to locate a teeter bed 29 intermediate inlet 27 and the bottom outlet of tank 7 3. The teeter bed, as shown in Fig. 2, comprises a f peller 8 which preferably after the equilibrium stage is reached.

screen 31 supporting a bed of shot 32. In a typical installation, a ten mesh screen may be utilized for this purpose, and the shotsize will be on the order of A to W diameter. With this arrangement each impulse of the pulsator mechanism 25 discharges the contents of its displacement unit 24 through line 26 into inlet 27 and thence upwardly at increased velocity under the restriction of bushing 28 to strike the shot and associated settled solids supported on screen 31 with suflicient force to elevate them substantially. The pulsing interval is estab lished to provide a period of free settling after each such elevating movement, and the loosening of the shot bed permits the heavier solids to work through the interstices and descend into or toward the bottom of extension member 6 for removal of the induced flow through line 12.

' When the unit is started, feed is delivered into tank 3 without actuation of parts other than impeller 8 until it begins to overflow. The pulsating mechanism is then operated in the manner just described and each pulsation crowds suspended solids into the body of material in tank 5 moving under centrifugal influence, with the result that the density of such material is progressively increased until an equilibrium' stage is reached. This causes the lighter constituents being carried in the centr'ifugal movement to rise to the surface and overflow, while theheavier constituents will settle into extension 6 by reason of the density and movement of the material in tank,5.

After the equilibrium stage is reached, an analysis of overflow will indicate the efficiency of the operation. If too much of the heavier constituent appears in the overflow product, it may be necessary to reduce the stroke maintain enough upcast flow to maintain a proper density condition in tank 3 to assure anjadequate overflow .of.

lighter constituents.

Once the final setting of the machine is made as aforesaid, the operation continues without further adjustment. It is desirable to havea variable speed drive on the imcomprises two blades at as shown. The impeller will to determine the proper speed for a given type of pulp.

I be rotated within the range of'S-GO rpm. and some initial adjustment will be required,

Once this adjuste ment has been determined, the operation can continue without further adjustment.

Periodic sampling will indicate changed efliciency due tcr variations in feed, content orv similar causes and. therequired. adjustments may. be. made without a shutdown as. conditions require. However, if velocity changes are necessary, it will be necessary tostop and drain the machine to substitute one. size bushing 28 for another. In. such event, the other adjustments may bemade when operation resumes.

It should be'understood that different operational con trols will be utilized. in. different treatments which a given machine performs. .The machine may be operated alone or in series for the various purposes, and particularly in iron ore treatments, it will be preferable to. utilize a first stage for desliming and to produce a coarse concentrate. which may be ground and retreated. to. obtain a higher concentration. Such practices are illustrated in the. following. examples:

Test No. 1 illustrates a typical upgrading operation with the teeter bed eliminated.

Original feed, classifier overflow, minus 35 mesh.

Hematite iron ore. Feed ground in rod'rnill sixmim utes and deslimed.

Feed wash1300 cc./min.

Back .wash2000 ccJ/ min.

Super elevation-15";

20 r.p.m. onthe impeller. 12,0 pulsations. through: discharge! A Discharge: plus. closed discharge; valvce untiliconer? or separatingzonewas fully. charged: Discharge valve opened slightlyior balance; of: test; as second-i; orifice:

Test No.2,. is similar to Test No.,1'; .the originalifeed was deslimed but not preground. before treatment.

Original, feed. Classifier overflow, minus3f5 mesh... Hematite iron ore. 1 Feed was run through machine for deslimingg fand'to' produce a rougher concentrate, to be retreated;

Feed wash2700*cc./min.-

Back wash-1020 ccL/min.

No overflow. "'concentrates (2) orifices discharge. 20' r.p.m. on the impeller.

120 pulsations.

Super elevation-12 inches.

Running time twohours.

Percent Percent Fe in Percent Wt; W 'Fe feed Distributton Gleaner C(metS 5, 310 9.41 54. 5.08 15.:13 Cone Resldue; 2,493 i 4. 42 385 70 l. 71 :09 Cleaner Tallings ,765 33:24 32.44. 10.-78.- 32.09. Slime Talllngs 29, 882 52. 93 30. 26 16.02 47. 69

wanna-g ams..." 50.450 100.00% 3:559. .100.. 0%;

" "imam- 5 5 4c) Screen analysis of thecleaner cell concentrates;

Wt. Percent Percent Fe in Percent Wt. Fe feed Dist.

100 ltd-508* 66.35 10.67 2 19:69

Pulsator R.p.m'.. (impeller) 26 Feed Wash cc./rnin. 20.00 Back wash .cc,/rnin. 1100. Super. elevation inches v 3 No overflow. Runningvtimehours 7.5-

Percent Percent Fe in Percent Wt. Wt; Fe. 1 feed. 'DlSill'ir button v Rougher Comets." 21,852 1 41190 36.44 "15.27 O 60.72 Slime ta1lings. 38, 022 1 58.10 1 17.00 9.88 L 39.2% 00;474 100.00 I 25.15 100.00;

V Rougher; Concentrates, 27,852 grams, was ground-in- Rod Mill. for: six minutes, and. retreated.

Pulsator. Rpm. (impeller) 26" Feed wash cc./min. 2000' Back wash cc./min. 1100: Super elevation inches 10' No overflow.

Running time hours 2.5

Forthis example test. Screen and shot bed-were added to the machine.

In another series oftests tod'emonstrate the effectiveness of the jig in deslirning operations, comparisons'wereundertaken between different rates ofoackwashflOwand as to-the eflect of the-teeter bed insuch operations. The" results-'ofthese' tests follow:

Test No. 4: used backwash in the" amount of- 3 10 ccz/rnin. and produced a tailing havingonlyl177%'- by weight inthe +325 mesh sizes and 98.23 in the-3 25' mesh sizes. 7

Original feed classifier overflow, minusv 3'5'mesh. 5 Hematite iron: ore. a Usingthemachineas'deslimer;

Rulsator. 56;

R;p.-m. (impeller) 8%. Feed.wash:... ......j.. 110.0 ccJmin: Back wash 1280 cc./min.

6 Overflow 970 cc./min. flowed to waste through overflow- Percent Percent Fe in Percent Backwash used 310 cc./min. Fe feed t Super elevation 1%". Discharge 1".

Running time lhour and 27 minutes. 5 ggfifi fi'gsii sjii 'I 3133 14-89 i No shot bed as as as as 2:

Welghtingrams 11,932 100.009: 26. 22 100. 00% W Pwent Percent Fe in Percent 10 a feed Screen analysis of tailings gave the following results.

Concentrates 2, 265 26. 49 29. 20 7. 74 30. 98 Wt. Percent Gone Residue 3, 850 45. 03 23. 80 10. 72 42. 92 Wt. Tallings plus 325 mesh 43 50 11. 50 06 24 Tailings minus 325 mesh- 2, 392 27.98 23.10 6.46 25.86 'Iaillngs plus 325 mesh .2, 841 37. 31 8, 550 100. 00 24. 98 100. 00 Tailings minus 325 M 4, 77a 62. 69

7,614 100.00 Screen analysis of tailmgs gave the followmg results. order to facilitate draining of tank 5 as when intep changing bushings 28 or for repair and adjustment of Wt. Percent parts, a plug 35 is located in the extension portion 6, Wt. referably above the teeter bed as shown in Fig. 2, so that the solids of thepulp will not pack the bed of shot 32 as Edit?fiiifii zii tjjj::::::::::::::::::::::: 2,333 235 F Qbviwsly arrangement may be substituted 1f deslred.

' 21435 1 It will be apparent from the foregoing examples that the practice of the present. invention may be adapted to i a variety of treatments and adequate controls are pro- ....tzzrittreatments a w to of from Sn er elevation causea +325. mesh character. Since there Will be considerable variation in i the properties of an ore of a given type and widespread mm tallmgs variations between ores of different types, initial testing p l 5 will be necessary to determine the proper controls for a (impeller) 3 given treatment. Thereafter, slight variation in the con- F wash 1100 i trols as previously described will suffice to maintain the a Back wash 1400 (XL/min. p q la maximum efiiciency- Overflow None. 91am: Super elevation 3" 1. Apparatus for the treatment of solids in liquids com- Discharge 1", 40 prlslng a tank for pulp having a top overflow for lighter Running time 1 h and 40 i particles and a bottom discharge outlet for heavier particles, means for delivering a pulp to be treated into the upper portion of the tank at a point below the overflow Percent Percent Fein Percent level, a rotary impeller for imparting centrifugal move- Fe feed ment to pulp in the tank, a hollow member disposed in pressure-confining relation to the discharge outlet and exconcentmtes 3,907 19 28.45 1229 16 tending downwardly therefrom for a substantial distance, Cone Residue 340 3. 76 29. 30 1.10 4. 40 pressure-confining means for removing settled solids from $3555: g if i g ggfg- @233 5252 $152 3:23 the lower end of said hollow member in an induced flow, i H 50 separator means disposed in the hollow member interweightmgmmsmm 9045 2500 mediate its ends, a hydraulic pulsator in communicating connection with the hollow member below the separator A part of the tailings used for screen analysis gave the means for direcfi] 1g liquid i a pulsating flow upwardly following results. through the sepalator and into the tank, and means as soclated with said hollow member for varying the volume of liquid directed through the separator and into the tank.

wt percent 2. Apparatus for the treatment of solids in liquids com- Wt. prising a tank for pulp having a top overflow for lighter particlesand a bottom discharge outlet for heavier par T sn u 325 mesh 62 22-05 30 ticles, means for delivering a pulp to be treated into the {Railings EJ111832; mesh f 219 7794 upper portion of the tank at a point below the overflow 281 0- level, a rotary impeller for imparting centrifugal move- In Test No. 6, using a 4 /2" super elevation and a back- 65 wash flowof 2300 cc./min., a good concentration was noted with a 26.22 iron in feed upgraded to 41.15%.

ment to pulp in the tank, a hollow member disposed in pressure-confining relation to the discharge outlet and etc tending downwardly therefrom for a substantial distance, pressure-confining means for removing settled .solids from the lower end of said hollow member in an induced flow, separator means disposed in the hollow member intermediate its ends, a hydraulic pulsator in communicating connection with the hollow member below the separator means for directing liquid in a pulsating flow upwardly through the separator and into the tank and means associated with said hollow member for varying the velocity otliquid directed through the separator and into the tank.

3. Apparatus for the treatment of solids in liquids com shamanprising a tank for pulp having atop overflow for lighter" level, a variable-speed. rotary impellerfor impartingcen trifugal movement to pulp in the tank, a hollow member disposed in pressure-confining relation to the discharge outletand evtending downwardly therefrom for a sub.- stantial distance, pressure-confining means for removing settled solids from the lower end'. of said hollow member, separator means disposed in" the hollow member intermediate its ends, a hydraulic pulsator in communicating connection with the hollow member below the separator means for directing liquid in a pulsating flow upwardly through the. separator and into the tank, and. meansassociated with said hollow member for varying; the; volume of liquiddirected through the separator and into the tank.

4'. Apparatus for the treatment of solids in liquids comprising a tank. for pulp. having a. top. overflow for lighter particles and a bottom discharge outlet for heavier particles, means for delivering a pulp to. be treated into the upper. portion of the tank at'a point below the overfi'ow, level, a rotary impeller for imparting centrifugal movement to pulp in the tank,. a hollow: member communicating with the discharge outlet and extending downwardly therefrom for asubstantial distance, means, including a. pump, for removing s'ettledj solids fromjthe. lower end of said hollow member, separator. means disposed in the hollow member intermediate its, ends ,,a hydraulic pulsator incommun-icating connection with the hollow member below the separator meansfor directing.

a pulsating flow through. the. separator and into the tank, and means associated with said hollow member for varying the volume 'of liquid directed throughthe separator and into the tank. a

5-. Apparatus for the treatment of solids in liquids comprising a tank for pulp having a top overflow for lighter particles. and a bottom discharge outlet for heavier particles, means for delivering a pulp to. be treated into the. upper portion of the tank at a point below the. overflow level, a rotary impeller for imparting centrifugal movement to pulp in the. tank, a hollow member disposed. in pressure-confining relation to the discharge outlet and. extending downwardly therefrom for a substantial distance, pressure-confining means-for removing.

settled solids fromthe lower end of said hollow member, separator means including a screen and a bed of shot on the screen disposed in the hollow member intermediate its ends, a. hydraulic pulsator in communicating connection with the hollow member belowthe separator means for directing liquid in a pulsating flow upwardly through the separator andinto the tank under sufficient force to elevate the shot, and means associated with said hollow. member for varying the volume of liquid directed'through the separator and into the tank.

6. Apparatus for the treatment of, solids. in liquids comprising a tankfor pulp having a top overflOW for, lighter particles and a bottomdischarge: outlet-for heavier particles, means for delivering a pulp to be treated into. the upper portion of the tank at a point below. theoverflow level, a rotary, impeller for imparting. centrifugal movement to pulp in the tank, a hollow member. disposed in pressure-confining relation to the. dischargeoutletand'. extending downwardly therefrom for. a. substantial. disstance, pressureconfining means. for removing settled.

solids from the lower end of. said hollow member, sep-- arator. means disposed in the.- hollow member intermediate its ends, a hydraulic. pulsator in communicating.

connection with the hollow member. belowthe separator means for directing. liquid in a. pulsating. flow upwardly through the separator and into. the tank, andimeans ineluding an interchangeable orifice positionedinthe hollow member between said separator andj said pulsator con;-

nection: and" arranged to provide a selective velocity flow, into'theseparatore i into the upper portionof the tank at' a point below-the overflow'l'evel', a rotary impeller for impartingcentrifugal movement to pulp in the tank, a hollow member disposed in pressure-confining relation to the discharge outlet and extending downwardly therefrom for a substantial distance, pressure-confining means for removing settled solids from the lower end of saidhollow member, separator means disposed; in the hollow member intermediate its ends, an adjustablestrokehydraulic pulsator incommuni-- cat-ing connection with :the hollow member below the sep-- arator means for'directing liquid in; apul'satingflow upwardly through the. separator and; into the tank, and means. associatedwithsaidhollow member. for. varying the volume of liquid directed through the separator and into the-tank. r

8. Apparatus for the treatment of solids in liquids comprising a tank for pulp having a top overflow for lighter particles and a bottom discharge outlet for heavier particles, means for delivering a pulp to be treated into the, upper portion of the tank at a point below. the' overflow level, a rotary impeller for impartingcentrifugali.

arator means diSPOSfiddil Ihe hollow member intermediate.

its ends, a hydraulic pulsator in communicating CODHVBG," tion with the hollow member below the separator means for directing liquid in a pulsating flow-upwardly-through the separator and into thetank, a reservoir supplying liquid to the;pulsator having aliquid level'substantiall'y above the overflowlevelin the-tank, andmeans for varying the liquid level in thereservoir so as to vary the volume of flow initiatedby the-pulsation:

9. Apparatus as defined in-claimS in-which the'screenis l'Umesh and the=shot is approximately A inch-diameter size.

10. The method of recovering iron constituents of taconite ores and the like, which comprises forming an aqueous pulp of taconite ore of -10 mesh or finer sizes, introducing the pulp' into the upper-portion of a confined treatment zone of substantial vertical extent, subjecting material in; the upper portion of said: confined zone. to a-' centrifugal movement, inclusive of' an overflow ofrock constituents from the surface of -said material,.increasing the. density ofmaterial" in said.centrifugalmovement until an equilibrium is reached causing rock constituents to pass to the surface and ironfconstituents to: descend by gravity to the lower limits of the vertical. zone, irn: peding said gravitational descent by maintaining a screen and a bed of shot thereon across the zone intermediate its ends, removing settled iron from the lower end of the. vertical. zone by an induced flow, and dir ecting hydraulic pulsations upwardly through the zone from, a point between the. screen. so. as tointermittently elevate the shot and associated solids from the screen and crowd high specific gravity constituents into the centrifugal material, the interval between: pulsations being; long;- enough. to permitv a; free settling. of iron constituents throughout the: vertical extent .of said zone below theicentrifugal material: andto. let the shot come to rest on the screen.

11. The method of recovering iron constituents off 7 taconite ores and the like, whichcomprises-.formrng an.

material in the uppenportion of said. confinedt zone to: a; centrifugal movement, inclusiveof-an overflow of: rock: constituents from the surface. of saidnnaterial', increasing;

and. thepointofi iron removalinto the upper portion of. a' confined.

the density of material in said centrifugal movement until an equilibrium is reached causing rock constituents to pass to the surface and iron constituents to descend by gravity to the lower limits of the vertical zone, impeding said gravitational descent by maintaining a screen and a bed of shot thereon across the zone intermediate its-ends, removing settled iron from the lower end of the vertical zone by an induced flow, directing hydraulic pulsations upwardly through the zone from a point between the screen and the point of iron removal so as to intermittently elevate the shot and associated solids from the screen and crowd high specific gravity constituents into the centrifugal material, the interval between pulsations being long enough to permit a free settling of iron constituents throughout the vertical extent of said zone below the centrifugal material and to let the shot come to rest on the screen, and varying the velocity of flow in the hydraulic pulsations in accordance with the settling rate of the iron.

12. The method of recovering iron constituents of taconite ores and the like, which comprises forming an aqueous pulp of taconite ore of 10 mesh or finer sizes, introducing the pulp into the upper portion of a confined treatment zone of substantial vertical extent, subjecting material in the upper portion of said confined zone to a centrifugal movement, inclusive of an overflow of rock constituents from the surface of said material, increasing the density of material in said centrifugal movement until an equilibrium is reached causing rock constituents to pass to the surface and iron constituents to descend by gravity to the lower limits of the vertical zone, impeding said gravitational descent by maintaining a screen and a bed of shot thereon across the zone intermediate its ends, removing settled iron from the lower end of the vertical zone by an induced flow, directing hydraulic pulsations upwardly through the zone from a point between the screen and the point of iron removal so as to intermittently elevate the shot and associated solids from the screen and crowd high specific gravity constituents into the centrifugal material, the interval between pulsations being long enough to permit a free settling of iron constituents through the vertical extent of said zone below the centrifugal material and to let the shot come to rest on the screen, and varying the volume of flow in the hydraulic pulsations in accordance withvthe settling rate of the iron.

13. The method of classifying solids in liquids which comprises 'forming an aqueous ore pulp containing a plurality of solids constituents of ditferent specific gravity and in finely divided condition, introducing the pulp into the upper portion of a confined treatment zone of substantial vertical extent, subjecting material in the upper portion of said confined zone to a centrifugal movement, inclusive of an overflow of lighter constituents from the surface of said material, increasing the density of material in said centrifugal movement until an equilibrium is reached causing lighter constituents to pass to the surface and coarser constituents to descend by gravity to the lower limits of the vertical zone, impeding said gravitational descent by directing hydraulic pulsations upwardly through the zone so as to crowd high specific gravity constituents into the centrifugal material, the interval between pulsations being long enough to permit free settling of heavier constituents throughout the vertical extent of said zone, removing settled solids from the lower end of the vertical zone by an induced flow, and changing the force of the pulsations directed against the material in centrifugal movement in relation to a determination of the quantity of coarser constituents in the overflow products.

14. The method of classifying solids in liquids which comprises forming an aqueous ore pulp containing a plurality of solids constituents of different specific gravity and in finely divided condition, introducing the pulp into the upper portion of a confined treatment zone of substantial vertical extent, subjecting material in the upper portion of said confined zone to a centrifugal movement, inclusive of an overflow of lighter constituents from the surface of said material, increasing the density of material in said centrifugal movement until an equilibrium is reached causing lighter constituents to pass to the surface and coarser constituents to descend by gravity to the lower limits of the vertical zone, impeding said gravitational descent by directing hydraulic pulsations upwardly through the zone so as to crowd high specific gravity constituents into the centrifugal material, the interval between pulsations being long enough to permit free settling of heavier constituents throughout the vertical extent of said zone, removing settled solids from the lower end of the vertical zone by an induced flow, and changing the force of the pulsations directed against the material in centrifugal movement in relation to a determination of the sizes of the constituents in the overflow product.

References Cited in the file of this patent UNITED STATES PATENTS 1,151,722 Schiechel Aug. 31, 1915 1,895,505 Wuensch Jan. 31, 1933 2,064,109 Hadsel Dec. 15, 1936 2,242,020 Wood May 13, 1941 2,466,120 Nawman Apr. 5, 1949 

